In order to increase frequency usage efficiency, research into cognitive wireless technology has been advanced, wherein a wireless communication apparatus recognizes and identifies a surrounding electromagnetic wave environment, and adaptively changes the frequency, wireless method and the like, used for wireless communications. In particular, a mode has been conceived in which unlicensed users (secondary users) are able to use frequencies that have been allocated to licensed users (primary users) but are not actually in use. A frequency of this kind is called a secondarily usable frequency, or a “white space”. When a secondary user is to use a white space of this kind, it is necessary to determine the available frequencies and to determine which of the frequencies is desirable to use.
In recent years, the use of spectrum (white space) databases has been investigated in order to assist rapid decision-making about the available frequencies (Non-Patent Document 1). By acquiring an available frequency from such a database, a secondary user can expect a rapid decision about the frequency to be used for communication.
Furthermore, the application of cognitive wireless technology using white spaces to vehicular (moving object) communications has also been investigated. The characteristic features of cognitive wireless technology for vehicular communications is that the location of the vehicle changes frequently, and consequently the available frequencies change frequently.    Patent Document 1: Japanese Patent Application Publication No. 2009-200773    Non-Patent Document 1: Google Inc. “Proposal by Google Inc. to Provide a TV Band Device Database Management Solution”, [online], (retrieved on 17 Oct., 2011), (URL: http://www.scribd.com/doc/24784912/01-04-10-Google-White-Spaces-Database-Proposal)